Is the human brain designed to be honest about itself?

Doesn’t look like we’re sure, but there’s good reason to believe we’re not the logical machines some might like to believe:

The medial prefrontal cortex exhibits a higher resting metabolic rate than many other brain regions. This physiological default mode might support a psychological default state of chronic self-evaluation that helps people consider their strengths and weaknesses when planning future actions. However, a recent imaging study that relates medial prefrontal cortex activity to self-evaluation raises new questions about whether the psychological default mode of self-evaluation is best characterized by accurate self-evaluations or by feeling good about yourself.